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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Non-contact Creep Resistance Measurement for Ultra-high temperature Materials

Continuing pressures for higher performance and efficiency in propulsion are driving ever more demanding needs for high-temperature materials. Some immediate applications in spaceflight include combustion chambers for advanced chemical rockets and turbomachinery for jet engines and power conversion in nuclear-electric propulsion. In the case of rockets, the combination of high stresses and high temperatures make the characterization of creep properties very important. Creep is even more important in the turbomachinery, where a long service life is an additional constraint. Some very high-temperature materials are being developed, including platinum group metals, carbides, borides, and silicides. But the measurement of creep properties at very high temperatures is itself problematic, because the testing instrument must operate at such high temperatures. Conventional techniques are limited to about 1700 C. A new, containerless technique for measuring creep deformation has been developed. This technique is based on electrostatic levitation (ESL) of a spherical sample, which is heated to the measurement temperature and rotated at a rate such that the centrifugal acceleration causes creep deformation. Creep of samples has been demonstrated at up to 2300 C in the ESL facility at NASA MSFC, while ESL itself has been applied at over 3000 C, and has no theoretical maximum temperature. The preliminary results and future directions of this NASA-funded research collaboration will be presented.

Hyers, Robert W.↗
DOE OSTI2016

Frequency and field dependent dynamic properties of CoFe{sub 2−x}Al{sub x}O{sub 4} ferrite nanoparticles

Highlights: “CoFe{sub 2−x} Al{sub x}O{sub 4} ferrite nanoparticles: Static and dynamic properties” • Grain size reduction with Al{sup 3+} content. • Reduction in Ms, Hc, with increasing Al{sup 3+} content. • Increase in resonance frequency with applied field. • Decrease in resonance field with increase in Al{sup 3+} content. • Decrease in Gilbert parameter with increase in Al{sup 3+} content. - Abstract: Aluminum doped CoFe{sub 2−x}Al{sub x}O{sub 4} (0 ≤ x ≤ 0.9) nanoparticles were synthesized via auto-combustion. Formation of single phase cubic spinel structure was confirmed by X-ray diffraction (XRD) analysis. XRD analysis suggests a linear decrease in lattice cell parameters and grain size (90–55 nm) with the increase in Al{sup 3+} content. The saturation magnetization of samples decrease with increasing Al{sup 3+} content due to magnetic dilution effect. A concomitant linear reduction in coercivity was also observed mainly due to decrease in magnetic anisotropy. Frequency and field dependent dynamic properties of nanoparticles were studied by ferromagnetic resonance (FMR) technique. The resonance frequency increases linearly with magnetic field for all nanoparticles. Magnetic field dependent experimental absorption data (S{sub 21} vs. frequency) were compared with effective medium theory considering an effective demagnetization field and was observed to be in good agreement with each other. High Al{sup 3+} content reduces the Gilbert damping parameter thus making CoFe{sub 2−x}Al{sub x}O{sub 4} as an attractive material for high frequency applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Photoionization of seeded combustion products as a method of enhancing the efficiency of magnetohydrodynamic power generators

Here, in this study, we performed an experimental and computational investigation into the feasibility of utilizing photoionization to enhance the electrical conductivity of seeded oxy-fuel combustion products and improve the performance of magnetohydrodynamic (MHD) power generators. We applied a variety of optical and microwave diagnostics to study the ionization and recombination processes of potassium excited by an excimer laser in a high-velocity oxy-fuel free jet. Computational fluid dynamic (CFD) simulations were performed to model the thermophysical properties and species densities of the free jet. The CFD results were validated with position-dependent potassium concentration measurements. Electron recombination exponential lifetimes were measured through time-resolved microwave transmission. The experimental electron lifetimes were compared with lifetimes calculated from CFD-predicted species densities and literature recombination rates. It was determined that K + or O 2 are the most likely recombination partners for photoionized electrons. Time-resolved fluorescence measurements provided evidence of an ionization pathway involving a two-photon ionization of KOH . Finally, a zero-dimensional chemical kinetic model was developed to assess the fundamental viability of inducing a non-equilibrium electron population to provide a net energy return in combustion-driven MHD power generators. We determined that a high energy return is feasible for targeting electrode boundary layers with ultraviolet photoionization. We also found that photoionization could potentially lower the required temperature of the bulk gas flow.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRSDate not supplied

Cryogenic Extension of NASA Species Polynomials Using Hydrogen and Oxygen at Stoichiometry

NASA has been conducting research in Rotating Detonation Rocket Engines (RDREs) for several years. A recent test at the Marshall Spaceflight Center has successfully shown operation of a RDRE that ran for 251 seconds which had combustion chamber cryogenic inlet conditions [1]. However, an overall pressure gain was not observed in the performance of the engine. Such an indication could mean an optimal chamber design is yet to be discovered. Such a design could significantly reduce parasitic pressure loses and improve overall engine efficiency beyond that of conventional rockets. To investigate different chamber configurations, new CFD capability is needed to accurately capture cryogenic thermophysical and transport property data. Such an effort is currently part of NASA’s Early Career Initiative (ECI) program. This paper focuses on the thermophysical property mixture model approach that makes use of NASA’s polynomial fits of species and another cryogenic model chosen from NIST’s Refprop program. Presented in this paper are results of a 1D denotation CFD simulation of stoichiometric Hydrogen and Oxygen mixture at a cryogenic upstream condition.

Combustion↗
DOE OSTI2020

A phenomenological rate of injection model for predicting fuel injection with application to mixture formation in light-duty diesel engines

Fuel injection rate laws are one of the most important pieces of information needed when modeling engine combustion with computational fluid dynamics. In this study, a simple phenomenological model of a common-rail injector was developed and calibrated for the Bosch CRI2.2 platform. The model requires three tunable parameter fits, making it relatively easy to calibrate and suitable for injector modeling when high-fidelity information about the internal injector’s geometry and electrical circuit details are not available. Each injection pulse is modeled as a sequence of up to four stages: an injection needle mechanical opening transient, a full-lift viscous flow inertial transient, a Bernoulli steady-state stage, and a needle descent transient. Parameters for each stage are obtained as polynomial fits from measured injection rate properties. The model enforces total injected mass, and the intermediate stages are only introduced if the injection pulse duration is long enough. Experimental rates of injection from two separate campaigns on the same injector were used to calibrate the model. The model was first validated against measured injection rate laws featuring pilot injections, short partially premixed combustion pulses, and conventional diesel combustion injection strategies. Then, it was employed as an input to engine computational fluid dynamics simulations, which were run to simulate experiments of mixture formation in an optically accessible light-duty diesel engine. It was found that, though simple, this model is capable of predicting both pilot and main injection pulse mass flow rates well: the simulations yielded accurate predictions of in-cylinder equivalence ratio distributions from injection strategies for both partially premixed combustion and pilot injections. Also, once calibrated, the model produced appropriate results for a wide range of injected mass and rail pressure values. Finally, it was observed that usage of such a relatively simple model can be a good choice when high-fidelity injection rate input and highly detailed information of the injector’s geometry and operation are not available, particularly as noticeable discrepancies can be present also among different experimental campaigns on similar hardware.

42 ENGINEERING↗
DOE OSTI2019

Effects of Fuel Properties on Particle Number and Particle Mass Emissions from Lean and Stoichiometric Gasoline Direct Injection Engine Operation

Engine-out particle size distributions and soot mass emissions were measured from a gasoline direct injection (GDI) engine fueled by seven different gasoline formulations. Additionally, particle size distributions were simultaneously measured downstream of a catalyzed gasoline particulate filter (GPF) to determine the size resolved filtration efficiency. Stoichiometric, lean homogeneous, and lean stratified combustion modes were studied at four steady-state engine conditions. The particulate matter (PM) Index was calculated for each fuel as a function of the double bond equivalent and vapor pressure of the fuel components. There was generally poor correlation between particle number (PN)/PM mass emissions and the PM Index for steady state stoichiometric conditions with clean injectors, which emitted low particle concentrations. However, under high-load lean homogeneous conditions, there was good correlation between PN/PM mass emission and the PM Index, with the exception that the high ethanol content fuel produced significantly higher PM emissions than the other fuels. Under lean stratified conditions, most fuels produced similar particle size distributions and concentrations with the exception that the E50 fuel produced significantly lower concentrations than the other fuels. These results demonstrate the profound sensitivity of particle emissions from high ethanol content fuel to engine operating conditions. Additionally, these results show the predominant factor influencing particle formation is charge mixture formation, which fuel properties influence, but not as significantly as engine conditions. Here, the GPF reduced the tailpipe particle number concentrations by 60 - 95% and showed evidence of passive regeneration under higher load lean engine conditions (Temp>400°C, Lambda>1.3). Total PN filtration efficiencies ranged from ~60 % with a clean filter to greater than 95% with as little as 25 mg/L of soot loaded on the filter with a most penetrating particle size (MPPS) between 100 and 150 nm. The GPF results show that GPF regeneration can be achieved with the added fuel efficiency benefit of lean operation.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

Sorbent-based Oxygen Production for Energy Systems

Project DE-FE0024075 deals with the development of a high-temperature sorbent-based oxygen production technology. Sorbent-based oxygen production process utilizes oxygen-storage properties of Perovskites to (1) adsorb oxygen from air in a solid sorbent, and (2) release the adsorbed oxygen into a sweep gas such as CO2 and/or steam for gasification systems or recycled flue gas for oxy-combustion systems. Pure oxygen can be produced by the use of vacuum instead of a sweep gas to affect the pressure swing. By developing more efficient and stable, higher sorption capacity, newer class of materials operating at lower temperatures this process represents a major advancement in air separation technology. Newly developed perovskite ceramic sorbent materials with order-disorder transition have a higher O 2 adsorption capacity, 200 ºC lower operating temperatures, and up to two orders of magnitude faster desorption rates than those used in earlier development efforts. The performance advancements afforded by the new materials lead to substantial savings in capital investment and operational costs. Cost of producing oxygen using sorbents could be as much as 60% lower than a cryogenic air separation unit.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

Advanced Light-Duty SI Engine Fuels Research: Multiple Optical Diagnostics of Well-mixed and Stratified Operation.

Ever tighter fuel economy standards and concerns about energy security motivate efforts to improve engine efficiency and to develop alternative fuels. This project contributes to the science base needed by industry to develop highly efficient direct injection spark ignition (DISI) engines that also beneficially exploit the different properties of alternative fuels. Here, the emphasis is on lean operation, which can provide higher efficiencies than traditional non-dilute stoichiometric operation. Since lean operation can lead to issues with ignition stability, slow flame propagation and low combustion efficiency, the focus is on techniques that can overcome these challenges. Specifically, fuel stratification is used to ensure ignition and completeness of combustion but this technique has soot and NOx emissions challenges. For ultra-lean well-mixed operation, turbulent deflagration can be combined with controlled end-gas autoignition to render mixed-mode combustion for sufficiently fast heat release. However, such mixed-mode combustion requires very stable inflammation, motivating studies on the effects of near-spark flow and turbulence, and the use of small amounts of fuel stratification near the spark plug.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Mid-infrared Pulsed Upconversion Imaging in a Rotating Detonation Combustor

To meet the challenges associated with performing mid-InfraRed (IR) imaging in Rotating Detonation Combustors (RDCs), a novel pulsed mid-IR UpConversion Imaging (UCI) diagnostic has been implemented. UCI is an alternative to direct mid-IR detection that uses nonlinear optical frequency mixing to shift mid-IR wavelengths carrying a target image to shorter wavelengths that can be imaged with high-performance silicon-based CCD/CMOS cameras. This approach offers several favorable properties including high spectral selectivity, high temporal resolution, and superior low-light detectivity. A hydrogen-air research RDC was operated with carbon dioxide addition to allow pulsed UCI imaging of mid-IR luminosity within the combustion channel from spontaneous thermal emissions. The resulting measurements demonstrate high spatiotemporal resolution capable of imaging small structures near the supersonically propagating detonation wave front. The results show how this technique can be used to observe sharp gradients and millimeter-scale structures in the high-temperature, high-pressure zones RDC flow fields.

White, Logan W.↗
DOE OSTI2017

Characterization of Hydrocarbon Emissions from Gasoline Direct-Injection Compression Ignition Engine Operating on a Higher Reactivity Gasoline Fuel

Low temperature combustion engine technologies are being investigated for high efficiency and low emissions. However, such engine technologies often produce higher engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions, and their operating range is limited by the fuel properties. In this study, two different fuels, a US market gasoline containing 10% ethanol (RON 92 E10) and a higher reactivity gasoline (RON 80 E0), were compared on a Delphi’s second generation Gasoline Direct-Injection Compression Ignition (Gen 2.0 GDCI) multi-cylinder engine. The engine was evaluated at three operating points ranging from a light load condition (800 rpm/2 bar IMEP g ) to medium load conditions (1500 rpm/6 bar and 2000 rpm/10 bar IMEP g ). The engine was equipped with two oxidation catalysts, between which was located the exhaust gas recirculation (EGR) inlet. Samples were taken at engine-out, between the catalysts, and at tailpipe locations. In addition, part of the raw exhaust was diluted and sampled for HC speciation. Canisters and sorbent membranes were used to collect volatile HCs and semi-volatile HCs, respectively. Di-nitrophenyl hydrazine (DNPH) cartridges were also used for collecting oxygenated species. Results showed overall lower HC emissions with the RON 80 E0 fuel compared to the RON 92 E10 fuel. For both fuels, the percentage of aromatic HCs was higher in the exhaust than in the fuels themselves. High engine-out aldehyde and ketone emissions were observed for both fuels. The reported HC speciation information can be useful for the development of a robust emission control system.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1977

Zirconium modified nickel-copper alloy

An improved material for use in a catalytic reactor which reduces nitrogen oxide from internal combustion engines is in the form of a zirconium-modified, precipitation-strengthened nickel-copper alloy. This material has a nominal composition of Ni-30 Cu-0.2 Zr and is characterized by improved high temperature mechanical properties.

Whittenberger, J. D.↗
NASA NTRS1983

Latest developments in cryogenic safety

The Cryogenic Safety Manual, sponsored by the British Cryogenics Council, was published over 10 years ago. A new updated version is now available. Some general aspects of cryogenic safety are highlighted, and attention is drawn to some of the more unusual hazardous situations. An awareness of the physical properties of the cryogenic fluids being dealt with is important in directing attention to hazardous situations which may arise. Because of this, the more important properties of the cryogenic fluids are given, such as molecular weight, boiling point and freezing point. From these properties, hazardous situations can be deduced. There are hidden dangers that are not always easy to spot. Some of the unexpected hazards, most of which have led to deaths, are: asphyxiation (anoxia), frost bites and hypothermia, explosions, and combustion. The aim of this publication is to help bring about increased safety in the production and use of cryogenic products through a deeper appreciation of the scientific, technological and administrative steps which must be made if accidents, some fatal, are to be voided in the future.

Webster, T. J.↗
NASA NTRS1954

Performance comparisons of Navy jet mix and MIL-F-5624A (JP-3) fuels in tubular and annular combustors / Richard J. McCafferty

The performances of Navy Jet Mix and MIL-F-5624A (JP-3) fuels were compared in J33, J47, and NACA experimental annular combustion chambers. Combustion efficiencies, altitude operational limits, and carbon-forming tendencies wer determined and discussed. The results indicate that Jet Mix fuel can be utilized satisfactorily in a number of current turbojet engines over the normal operating range. Small differences in combustion efficiences and altitude operational limits existed between the two fuels but these differences depended on the particular combustor and simulated altitude and rotor speed condition. Excessive carbon deposition is not predicted for Jet Mix fuel, although this property may be marginal.

Mccafferty, Richard J↗
NASA NTRS2004

Flame Retardant Epoxy Resins

As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

Thompson, C. M.↗
NASA NTRSDate not supplied

Lean Blowout (LBO) Simulations in a Rich-Burn Quick-Quench Lean-Burn (RQL) Gas Turbine Combustor

The transient processes involving lean blowout (LBO) in a RQL combustor such as the single cup combustor in the National Jet Fuels Combustion Program (NJFCP) referee rig are simulated with the reduced mechanisms based on Hybrid Chemistry for two different fuels, Cat-A2 and Cat-C1. Cat-A2 fuel is Jet-A with average or nominal properties based on a survey of the Petroleum Quality Information System database. The Cat-C1, an alternative jet fuel, is a GEVO alcohol-to-jet (ATJ) fuel composed almost entirely of two highly-branched C12 and C16 iso-paraffins. Experiments conducted in the NJFCP referee rig established a stable flame at an equivalence ratio of 0.096 (the near LBO condition) as the starting condition for LBO tests performed with all Category A and C fuels. Simulations of the approach to LBO verify that a stable flame is established at the near-LBO condition for each fuel before reducing fuel flow rate (and thus equivalence ratio) in a step-wise manner. At each new equivalence ratio, the global heat release rate and total fuel evaporation time histories are monitored to verify a new stable flame condition has been established before performing the next reduction in equivalence ratio until the flame is approaching the blowout. Main conclusions are threefold: (1) For Cat-C1 fuel the equivalence ratio for LBO is around 0.087. (2) For Cat-A2 fuel the equivalence ratio for LBO is either 0.082 or 0.078 depended on the time span of equivalence ratio of 0.085. (3) The averaged difference from LES on LBO for Cat-C1 relative to Cat-A2 is 8.75% versus 7.8% from the experimental data.

LES, Lean blow out↗
DOE OSTI2017

FY2016 Propulsion Materials Annual Progress Report

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines and Fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1992

Lab-scale Lidar Sensing of Diesel Engines Exhausts

Combustion technology and its environmental concerns are being considered with increasing attention, not only for global-scale effects, but also for toxicological implications, particularly in the lift conditions of traffic-congested areas and industrial sites. Majority combustion by-products (CO, NO(sub x)) and unburned hydrocarbons (HC), are already subject to increasingly severe regulations; however other, non-regulated minority species, mainly soot and heavy aromatic molecules, involve higher health risks, as they are suspected to be agents of serious pathologies and even mutagenic effects. This is but one of the reasons why much research work is being carried out worldwide on the physical properties of these substances. Correspondingly, the need arises to detect their presence in urban environments, with as high a sensitivity as is required by their low concentrations, proper time- and space-resolutions, and 'real-time' capabilities. Lidar techniques are excellent candidates to this purpose, although severe constraints limit their applicability, eye-safety problems and aerosol Mie scattering uncertainties above all. At CNR's Istituto Motori in Napels, a Lidar-like diagnostic system is being developed, aimed primarily at monitoring the dynamic behavior of internal combustion engines, particularly diesel exhausts, and at exploring the feasibility of a so-called 'Downtown Lidar'.

Borghese, A.↗